Asphaltenes are high molecular weight hydrocarbons having a chemical structure that can include stacks of condensed aromatic rings. Due to their high molecular weight, asphaltenes can be found within the least volatile fraction after distillation of crude oil. Asphaltenes also can be found in oil sand along with minerals and other hydrocarbons. Among the other hydrocarbons, oil sand can include lignite and other low-rank coal phases.
Oil sand can be processed to recover hydrocarbons for upgrading into more valuable products, such as oil. Asphaltenes, however, do not behave in the same manner as other hydrocarbons in oil sand, so the same processes typically cannot be used to upgrade them. Thus, in certain conventional processes for recovering hydrocarbons from oil sand, the asphaltenes most often are separated along with the minerals, lignite and water into a tailings stream. Without further processing, the asphaltene-containing tailings can be damaging to the environment. Disposal of the asphaltene-containing tailings also can waste potentially valuable energy and materials.